Could you point me to a quote taken in context that does that? I just reread the document and fail to see where the manifesto questions an individuals capacity of doing a tech job. I'm honestly trying but fail to see the offense.
AFAIK the author questions whether the percentage of capable and willing individuals is the same between men and women [1].
The manifesto also contains this quote to put the above in context
> I’m also not saying that we should restrict people to certain gender roles; I’m advocating for quite the opposite: treat people as individuals, not as just another member of their group (tribalism).
[1]: I agree with his conclusion that a non 50/50 split is not necessarily bias. The reasoning can't be discussed without the removed references.
PS: > "everyone is stupid = has bad reading comprehension" I disagree with the equality in general but I think your interpretation is fair as well - we probably just disagree on the context (e.g. did people pay full attention or even read the article at all).